Typical wheelchair designs employ a sturdy frame supporting a seat assembly. The seat assembly includes arm rests and push bars to allow the wheelchair to be pushed by an aide. Attached to the rear of the frame is a pair of drive wheels. The drive wheels are typically large diameter wheels attached to a central hub with spokes. Push rims are mounted to the drive wheels to allow the wheelchair occupant to propel the chair using their arms and upper body. A smaller pair of pivoting castor wheels is attached to the front of the frame to provide steerability. Extending down from the lower front of the wheelchair frame is a footrest system to support the lower legs. The footrest system typically includes a pair of bars, one mounted to each side of the frame. Attached to each bar is a footrest, which typically may be pivoted up and out of the way to provide clearance if the occupant so desires. Adjustment mechanisms allow each bar to slide in adjustment relative to the frame to accommodate the differing heights and leg lengths of the wheelchair occupant.
One drawback to existing wheelchairs is that the footrest system, once adjusted for the particular size of the occupant, remains locked in a fixed position. As a result, the occupant's legs are stationary while seated in the wheelchair. Over extended periods of time, a wheelchair occupant who is not able to move their legs on their own may develop atrophy in the leg muscles and contracture of the leg joint ligaments.
Muscular atrophy is a decrease in muscle mass resulting from, among other things, lack of use. Muscular atrophy begins within a few days after confinement to a wheelchair, and is a major factor preventing full recovery from leg injuries. Over longer periods of time, muscles in the leg may deteriorate completely.
Contracture of ligaments is a loss of elasticity resulting from lack of use. Like muscular atrophy, contracture may begin to set in soon after confinement to a wheelchair, and is a second major factor preventing full recovery from leg injuries. Extremely painful stretching exercises and other physical therapies are required to restore contracted ligaments to anything approaching pre-injury conditions.
Efforts have been made to prevent muscle atrophy and contractures by providing continuous motion of a wheelchair occupant's legs. For example, one prior art solution is provided by U.S. Pat. No. 5,324,060 issued to Van Vooren et al. The '060 patent discloses a wheelchair cycle apparatus that includes a frame to which is attached a connecting device for connecting the frame to a wheelchair. A drive wheel and driven wheel are attached to the frame. A pair of pedals are attached to either the drive wheel or the driven wheel depending upon whether the user can move his/her own legs. A chain connects the drive wheel to the driven wheel. The wheelchair cycle apparatus may be connected to the frame of a wheelchair to produce a wheelchair assembly that enables a disabled individual to exercise his/her own legs while seated in the wheelchair.
However, the wheelchair cycle apparatus shown in the '060 patent requires the disabled individual to assume a non-standard position in the wheelchair. Additionally, the forward-protruding cycle frame makes the wheelchair cycle apparatus occupy a larger envelope of space than does a conventional wheelchair. Since building accesses and other public services have been specifically designed to accommodate conventional wheelchairs, these public services may not accommodate the wheelchair cycle apparatus of the '060 patent.